1. Field of the Invention
This invention relates to novel (perhaloalkyl)thio-substituted aldehydes and ketones which are prepared by reacting the unsubstituted aldehyde or ketone with a perhaloalkanesulfenyl chloride. A further aspect of the invention relates to a novel process for preparing (perhaloalkyl)thio-substituted carbamates utilizing the aldehydes and ketones of the invention as essential intermediates. These carbamate derivatives have useful pesticidal activity.
2. Prior Art
Carbamate derivatives of ketoximes have been disclosed by Magee (U.S. patent application, Ser. Nos. 132,584 now abandoned and 229,207 now U.S. Pat. No. 3,875,232). Some of the carbamate compounds described therein contain alkylthio-substituents. The corresponding alkylthiosubstituted ketones from which these compounds are derived are prepared by a different method from that of the present invention. Instead of reacting the unsubstituted ketone with a sulfenyl chloride, the ketones are prepared by reacting a haloketone with a mercaptan in the presence of an acid receptor. No halogen-containing alkylthio-substituted ketones are disclosed by this reference, and although the compound 1-(3,3,3-trifluoropropylthio)-3,3-dimethyl-2-butanone O-methylcarbamoyloxime is mentioned, no method is given for its preparation, and the ketone starting material from which this compound is prepared is not disclosed.
Payne and Weiden [J. Ag. and Food Chem., 14 356 (1966)] have reported the preparation of trisubstituted acetaldehyde O-(methylcarbamoyl)oximes wherein one of the substituents may be an alkylthio group. The process utilized to obtain the aldehyde precursors of these compounds does not include a sulfenyl chloride as one of the reactants, and no halogen-containing alkylthio-substituted aldehydes are disclosed by this reference.
The reactivity of perhaloalkanesulfenyl chlorides is summarized by Karasch, The Chemistry of Organic Sulfur Compounds, Vol. 2, 137-165 (1966). No reactions of perhaloalkanesulfenyl chlorides with either aldehydes or ketones are given in this discussion. The reaction of trifluoromethanesulfenyl chloride with the ester compound sodium formyl acetic acid ester has been reported by Haas et al., Chem. Ber., 104, 1855 (1971).
Leir, J. Org. Chem., 37, 887 (1972) reported the reaction of disulfenyl chlorides with aldehydes and active methylene compounds. In this reference the difficulty of producing the substituted aldehyde without the occurrence of polymerization is discussed.
The reaction of sulfenyl chlorides, in general, with compounds containing active methylene groups is summarized by E. Kuhle, Synthesis, 1971, 617. Reaction of ethanesulfenyl chloride with acetone was found to yield hexaalkylthio-substituted acetone, Brintzinger et al., Chem. Ber. 87, 300 (1954). Chloroethanesulfenyl chloride is shown to react with acetone to produce chloroethylthioacetone, Fuson et al., J. Org. Chem. 11, 469, (1946).
From the above discussion of the prior art, one may be led to conclude that perhaloalkanesulfenyl chlorides would react with aldehydes and ketones in the same manner as nonperhalogenated alkanesulfenyl chlorides. However, this has not been found to be the case. For example, when methanesulfenyl chloride was reacted with tert-butyl methyl ketone, according to art-recognized procedures, (i.e. those prescribed for the reaction of ethanesulfenyl chloride with acetone), no reaction product could be obtained. It was therefore surprising to find that by substituting a perhaloalkanesulfenyl chloride for the nonperhalogenated reactant, the reaction proceeded without difficulty, and a perhaloalkylthio-substituted ketone was in fact obtained.
When nonperhalogenated alkanesulfenyl chlorides are reacted with aldehydes and ketones, e.g. acetone, the molar ratio of reactants is critical. Excess amounts of the sulfenyl chloride tend to produce poly-substituted alkythio-aldehydes and ketones, e.g. hexalkylthio-substituted acetone. When perhaloalkanesulfenyl chlorides are reacted with aldehydes and ketones according to the present invention, an excess amount of the sulfenyl chloride is not detrimental to the formation of monosubstituted products. The process of preparing compounds of the present invention minimizes the uncontrolled formation of poly-substituted alkylthio-substituted aldehydes and ketones.
The compounds of the present invention exhibit superior stability characteristics over known alkylthio-substituted aldehydes and ketones. This superiority is especially evident with respect to stability against oxidation.
A recent publication by Bayreuther and Haas, Chem. Ber., 106, 1418 (1973) describes the preparation of certain trifluoromethylthio-ketones through the use of trifluoromethanesulfenyl chloride. However, prior to the present invention, it is believed that perhaloalkylthio-substituted aldehydes or ketones have not been described.